Rotating turbomachine component having a tip leakage flow guide

ABSTRACT

A rotating turbomachine component includes a base portion and an airfoil portion extending from the base portion. The airfoil portion includes a first end connected to the base portion and a tip end portion that is cantilevered from the base portion. A tip leakage flow guide is provided at the tip end portion of the airfoil portion. The tip leakage flow guide includes one or more turning vane members configured and disposed to guide a leakage flow from the tip end portion at a flow angle that substantially coincides with a flow angle of gases flowing downstream from the rotating turbomachine component.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to the art of turbomachinesand, more particularly, to a rotating turbomachine component having atip leakage flow guide.

Many turbomachines include a compressor portion linked to a turbineportion through a common compressor/turbine shaft or rotor and acombustor assembly. The compressor portion guides a compressed air flowthrough a number of sequential stages toward the combustor assembly. Inthe combustor assembly, the compressed air flow mixes with a fuel toform a combustible mixture. The combustible mixture is combusted in thecombustor assembly to form hot gases. The hot gases are guided to theturbine portion through a transition piece. The hot gases expand throughthe turbine rotating turbine blades to create work that is output, forexample, to power a generator, a pump, or to provide power to a vehicle.In addition to providing compressed air for combustion, a portion of thecompressed airflow is passed through the turbine portion for coolingpurposes.

In some cases, the hot gases expanding through the turbine portion leakor pass over tip end portions of the turbine blades. In order to reduceleakage, manufactures maintain tight clearances between the tip endportions and stationary components of the turbomachine. Generally, sealsare provided on the stationary component or turbine shroud. Whileeffective, existing seals still allow a portion of the hot gases orleakage gases to pass over the tip end portion. The tight clearanceestablished by the seal causes the leakage gases to exit at an anglethat is generally parallel to an axis defined by a turbomachine rotor.In contrast, hot gases passing along the gas path exit the rotor bladesat an angle. Interactions between the leakage gases and the hot gasesflowing along the gas path create localized pressure drops that have anegative impact on turbomachine performance.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the exemplary embodiment, a rotatingturbomachine component includes a base portion and an airfoil portionextending from the base portion. The airfoil portion includes a baseportion and a tip end portion that is cantilevered from the baseportion. A tip leakage flow guide is provided at the tip end portion ofthe airfoil portion. The tip leakage flow guide includes one or moreturning vane members configured and disposed to guide a leakage flowfrom the tip end portion at a flow angle that substantially coincideswith a flow angle of gases flowing downstream from the rotatingturbomachine component.

According to another aspect of the exemplary embodiment, a method ofoperating a turbomachine includes passing hot gases from a combustorassembly toward a plurality of buckets, guiding the hot gases onto theplurality of buckets, directing the hot gases downstream relative to theplurality of buckets along a gas path at a first flow angle, passing aportion of the hot gases over a tip end portion of the plurality ofbuckets at a second flow angle that is distinct from the first flowangle, and guiding the portion of the hot gases from the tip end portionof the plurality of buckets at a third flow angle that substantiallycoincides with the first angle.

According to yet another aspect of the exemplary embodiment, aturbomachine includes a compressor portion, a combustor assembly fluidlyconnecting the compressor portion and a turbine portion mechanicallylinked to the compressor portion and fluidly connected to the combustorassembly. The turbine portion includes a rotating component having abase portion and an airfoil portion extending from the base portion. Theairfoil portion includes a first end connected to the base portion and atip end portion that is cantilevered from the base portion. A tipleakage flow guide is provided at the tip end portion of the airfoilportion. The tip leakage flow guide includes one or more turning vanemembers configured and disposed to guide a leakage flow from the tip endportion at a flow angle that substantially coincides with a flow angleof gases flowing downstream from the rotating turbomachine component. Aturning vane support member is positioned at the tip end portion. Theturning vane support member includes an upstream end and a downstreamend. The one or more turning vane members project outward from theturning vane support member

These and other advantages and features will become more apparent fromthe following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a schematic view of a turbomachine including a tip leakageflow guide in accordance with an exemplary embodiment;

FIG. 2 is a partial cross-sectional view of the turbomachine of FIG. 1;

FIG. 3 is a detail view of a rotating component of the turbomachine ofFIG. 1 including a tip leakage flow guide in accordance with anexemplary embodiment;

FIG. 4 is a perspective view of the tip leakage flow guide of FIG. 3having a plurality of turning vane members in accordance with one aspectof the exemplary embodiment;

FIG. 5 is a perspective view of the tip leakage flow guide of FIG. 3having a plurality of turning vane members in accordance with anotheraspect of the exemplary embodiment; and

FIG. 6 is a perspective view of the tip leakage flow guide of FIG. 3having a plurality of turning vane members in accordance with stillanother aspect of the exemplary embodiment.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 and 2, a turbomachine constructed inaccordance with an exemplary embodiment is indicated generally at 2.Turbomachine 2 includes a compressor portion 4 operatively connected toa turbine portion 6. A combustor assembly 8 is fluidly connected tocompressor portion 4 and turbine portion 6. Combustor assembly 8 isformed from a plurality of circumferentially spaced combustors, one ofwhich is indicated at 10. Of course it should be understood thatcombustor assembly 8 could include other arrangements of combustors.Compressor portion 4 is also linked to turbine portion 6 through acommon compressor/turbine shaft 12. With this arrangement, compressorportion 4 delivers compressed air to combustor assembly 8. Thecompressed air mixes with a combustible fluid to form a combustiblemixture. The combustible mixture is combusted in combustor 10 to formproducts of combustion that are delivered to turbine portion 6 through atransition piece (not shown). The products of combustion expand along agas path 18 of turbine portion 6 to power, for example, a generator, apump, or a vehicle or the like (also not shown).

In the exemplary embodiment shown, turbine portion 6 includes a housing19 that encases a first, stage 20 and a second stage 21 that define gaspath 18. First stage 20 includes a plurality of first stage stators ornozzles, one of which is indicated at 30, supported to turbine housing19 through a nozzle platform 31. First stage 20 also includes aplurality of first stage buckets or blades, one of which is indicated at32, mounted to a first stage rotor wheel 34. Blades 32 are spaced from astationary shroud member 35. Blades 32 include a base portion 38 and anairfoil portion 40. Airfoil portion 40 includes a first end 42 coupledto base portion 38 and a second end or tip end portion 44 that is spacedfrom stationary shroud member 35. Second stage 21 includes a pluralityof second stage stators or nozzles, one of which is indicated at 48supported to turbine housing 19 through a nozzle platform 49. Secondstage 21 also includes a plurality of second stage buckets or blades,one of which is indicated at 50. At this point it should be understoodthat the number of stages in turbine portion 6 could vary.

In accordance with an exemplary embodiment, turbomachine 2 includes atip leakage flow guide 60 that conditions tip leakage flow passing overtip portions of blades 32. As best shown in FIG. 3, tip leakage flowguide 60 includes a turning vane support member 64 mounted to tip endportion 44 of blade 32. Turning vane support member 64 includes anupstream end 66 that extends to a downstream end 68 through asubstantially planar surface 70. A seal element 74 extends fromsubstantially planar surface 70 into a pocket (not separately labeled)of stationary shroud member 35. Seal element 74 limits flow passing fromgas path 18 across tip end portion 44 of blade 36. However, whilereduced, some leakage flow does flow over tip end portion 44 despite thepresence of seal element 74. In order to reduce losses associated withthe leakage flow, one or more turning vane members 80 are positioned onturning vane support member 64. In the exemplary aspect shown, turningvane member 80 is arranged adjacent to downstream end 68. Turning vanemember 80 alters a flow path of the leakage flow.

Combustion gases flow along gas path 18 and pass over nozzles 30 and areguided toward blades 32. A first or main flow 85 passes over blades 32and a second or leakage flow 88 passes over tip end portion 44 along gaspath 18. Main flow 85 flows at a first flow angle as a result ofinteractions with blade 36. Leakage flow 88 flows at a second flowangle, that is distinct from the first flow angle, and which runsgenerally parallel to shaft 12. Turning vane member 80 is configured tocondition or turn leakage flow 88 exiting tip end portion 44 to create aturned flow 91 that returns to gas path 18 at a third flow angle thatsubstantially coincides with the first flow angle of main flow 85flowing downstream from blades 32. By matching the third flow angle withthe first flow angle, undesirable interactions between turned flow 91and main flow 85 are reduced. In this manner, turning vane member 80reduces losses within turbine portion 6 associated with pressurevariations along gas path 18 resulting from undesirable interactionsbetween leakage flow 88 and the main flow 85. In the event that nozzles30 form part of a last stage (not separately labeled) of turbine portion6, turning vane 80 may be configured to guide the leakage flow gases atan angle that generally corresponds to the flow angle of gases flowingdownstream toward and along a radial diffusion section (not shown) ofturbine portion 6 so as to enhance pressure recovery.

In accordance with one aspect of the exemplary embodiment illustrated inFIG. 4, turning vane member 80 takes the form of a plurality ofsubstantially linear vane members 97. Each vane member 97 includes afirst end 99 and a second end 100. Second end 100 is off-set relative tofirst end 99 such that vane members 97 are angled relative to, forexample, shaft 12. More specifically, vane members 97 are angled so asto generally correspond to an airfoil profile 102 of airfoil portion 40.In accordance with one aspect of the exemplary embodiment, the angle ofvane members 97 is substantially equal to or ±30° of a trailing edgeangle θ of airfoil profile 102. FIG. 5 illustrates turning vanes 106 inaccordance with another aspect of the exemplary embodiment. Turing vanes106 take the form of a plurality of curvilinear vane members 110 havingfirst and second curvilinear surfaces 112 and 113. In a manner similarto that described above, vane members 110 are angled so as to generallycorrespond to an airfoil profile 102 of airfoil portion 40. Inaccordance with one aspect of the exemplary embodiment, the angle ofvane members 110 is substantially equal to or ±30° of a trailing edgeangle θ of airfoil profile 102. FIG. 6 illustrates turning vanes 117 inaccordance with yet another aspect of the exemplary embodiment. Turningvanes 117 take the form of complex geometrical vane members 121. Complexgeometrical vane members 121 include a first vane member 123 and asecond vane member 124. First vane member 123 includes a first endsection 126 that extends to a second end section 127. Second vane member124 includes a first end portion 129 that extends from second endsection 127 of first vane member 123 to a second end portion 130. Secondend portion 130 is off-set relative to first end section 126 of firstvane member 123 and is angled so as to generally correspond to anairfoil profile 102 of airfoil portion 40. In accordance with one aspectof the exemplary embodiment, the angle of second end portion 130 issubstantially equal to or ±30° of a trailing edge angle θ of airfoilprofile 102. Regardless of form, the turning vanes condition the leakageflow to pass back into the gas path at an angle the substantiallycoincides with the main flow to reduce undesirable interactions.

At this point it should be understood that the exemplary embodimentsprovide a system for redirecting tip leakage flow back into the gas pathto reduce undesirable interactions with the main flow. Reducingundesirable interactions with the main flow leads to a reduction inpressure losses that may detract from turbine performance. It shouldalso be understood that while shown in connection with a gasturbomachine, the exemplary embodiments could also be employed in asteam turbomachine.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A rotating turbomachine component comprising: abase portion; an airfoil portion extending from the base portion, theairfoil portion including a first end connected to the base portion anda tip end portion that is cantilevered from the base portion; and a tipleakage flow guide provided at the tip end portion of the airfoilportion, the tip leakage flow guide including one or more turning vanemembers configured and disposed to guide a leakage flow from the tip endportion at a flow angle that substantially coincides with a flow angleof gases flowing downstream from the rotating turbomachine component. 2.The rotating turbomachine component according to claim 1, furthercomprising: a turning vane support member positioned at the tip endportion, the turning vane support member having an upstream end, and adownstream end, each of the upstream end and the downstream endprojecting beyond the tip end portion, the one or more turning vanemembers projecting outward from the turning vane support member.
 3. Therotating turbomachine component according to claim 2, wherein the tipleakage flow guide is arranged at the downstream end of the turning vanesupport member.
 4. The rotating turbomachine component according toclaim 1, wherein the one or more turning vane members comprise aplurality of substantially linear vane members extending across the tipend portion, each of the plurality of substantially linear vane membersincluding a first end and a second end, the second end being off-setrelative to the first end.
 5. The rotating turbomachine componentaccording to claim 1, wherein the one or more turning vane memberscomprise a plurality of curvilinear vane members extending across thetip end portion.
 6. The rotating turbomachine component according toclaim 1, wherein the one or more turning vane members comprise aplurality of complex geometrical vane members extending across the tipend portion.
 7. The rotating turbomachine component according to claim6, wherein each of the plurality of complex geometrical vane membersincluding a first vane member having a first end section that extends toa second end section, and a second vane member having a first endportion that extends from the second end section of the first vanemember to a second end portion, the second end portion being off-setrelative to the first end section.
 8. The rotating turbomachinecomponent according to claim 1, wherein the one or more turning vanemembers are arranged at an angle that generally corresponds to anairfoil profile of the airfoil portion.
 9. A method of operating aturbomachine comprising: passing hot gases from a combustor assemblytoward a plurality of buckets; guiding the hot gases onto the pluralityof buckets; directing the hot gases downstream relative to the pluralityof buckets along a gas path at a first flow angle; passing a portion ofthe hot gases over a tip end portion of the plurality of buckets at asecond flow angle that is distinct from the first flow angle; andguiding the portion of the hot gases from the tip end portion of theplurality of buckets at a third flow angle that substantially coincideswith the first flow angle.
 10. The method of claim 9, wherein passingthe portion of hot gases from the tip end portion includes guiding theportion of hot gases across one or more turning vane members arranged atthe tip end portion.
 11. The method of claim 10, wherein guiding theportion of hot gases across one or more turning vane members includespassing the portion of hot gases over a plurality of angled vanemembers.
 12. The method of claim 10, wherein guiding the portion of hotgases across one or more turning vane members includes passing theportion of hot gases over a plurality of curvilinear vane members. 13.The method of claim 10, wherein guiding the portion of hot gases acrossone or more turning vane members includes passing the portion of hotgases at an angle that generally corresponds to an angle of an airfoilportion of each of the plurality of buckets.
 14. A turbomachinecomprising: a compressor portion; a combustor assembly fluidlyconnecting the compressor portion; a turbine portion mechanically linkedto the compressor portion and fluidly connected to the combustorassembly, the turbine portion including a rotating component having abase portion and an airfoil portion extending from the base portion, theairfoil portion including a first end connected to the base portion anda tip end portion that is cantilevered from the base portion; a tipleakage flow guide provided at the tip end portion of the airfoilportion, the tip leakage flow guide including one or more turning vanemembers configured and disposed to guide a leakage flow from the tip endportion at a flow angle that substantially coincides with a flow angleof gases flowing downstream from the rotating component; and a turningvane support member positioned at the tip end portion, the turning vanesupport member having an upstream end and a downstream end, the one ormore turning vane members projecting outward from the turning vanesupport member.
 15. The turbomachine according to claim 14, wherein theone or more turning vane members is arranged at an angle that generallycorresponds to an airfoil profile of the airfoil portion.
 16. Theturbomachine according to claim 15, wherein the angle of the one or moreturning vane members is within no more than about 30° of a trailing edgeangle of the airfoil profile.
 17. The turbomachine according to claim14, wherein the one or more turning vane members comprise a plurality ofsubstantially linear vane members extending across the tip end portion,each of the plurality of substantially linear vane members including afirst end and a second end, the second end being off-set relative to thefirst end.
 18. The turbomachine according to claim 13, wherein the oneor more turning vane members comprise a plurality of curvilinear vanemembers extending across the tip end portion.
 19. The turbomachineaccording to claim 13, wherein the one or more turning vane memberscomprise a plurality complex geometrical vane members extending acrossthe tip end portion.
 20. The turbomachine according to claim 19, whereinthe plurality of complex geometrical vane members include a first vanemember having a first end section that extends to a second end section,and a second vane member having a first end portion that extends fromthe second end section of the first vane member to a second end portion,the second end portion being off-set relative to the first end section.